DE2325993A1 - ELECTRON CANNON - Google Patents

Description

Dip! - lng. Heinz Lesser, Pctentanwolt D -8 Munich 81, Cosimasiraße 81 · Telephone: (0811) 95 38

Kafoushik Kaisha Mcashi Seisakusho

Tokyo (Japan) L lQ _e 084 / Fl / hOo

Electron gun

The invention relates to an electron gun for electron beam irradiation systems with a pair on an insulating plate held electrodes for holding and supplying voltage to a thread and with a Wehnelt electrode »

Such an electron gun of known type, Figure 1 of the accompanying drawing _o "wherein two interconnected with a filament electrodes are secured to an insulating plate 2 and 3 connected to two provided on a insulating connection terminals 6 by an intermediate conductor 4 _o

lower part of the insulating block called 5 ■ holding Metallsylinders 7 <= · by an adjusting screw 5a corrected in their position -. is screwed a Wehnelt electrode 8 _ΰ through the bore 8a electron beams pass "On the other hand, a fastening ring 9 rotatable on the upper flange 7a of the cylinder 7 fixed =

In addition, a metal connecting part 12 is airtightly attached to a flange 10 a formed at the lower end of an electron gun insulator 10 by a seal 11. A 6et "inde formed in the upper end of the ring 9 engages in a thread formed on the lower end of the metal connecting part 12 (BIn ₁₇ so that by turning the ring 9 the flange 7a of the cylinder 7 at the lower end of the metal connecting part

_B is attached © in © to the upper part of each connection terminal

237 59P3

Dipl .-! Ng. Heinz Lesser, patent attorney D -8 Munich 81, CosimosicoBe 81 - Telephone: (0811) 95 38 20

6 fixed metal tongue 6a pressed against a respective power source terminal 14, which are fastened by means of an insulating material 13 in such a way that they seal the central opening of the metal connection part 12 «,

The metal connection part 12 is supplied with voltage for the Wehnelt electrode by an electrical line 15, which is led to the Wehnelt electrode 8 via the metal cylinder 7 mentioned.

As can be seen from the above, are hitherto conventional electron guns for electron irradiation facilities burdened with high production costs and because of their complicated construction relatively large "With electron gun ^ this type is 5 corrects the situation des'Isolierblocks by the 'adjustment screw 5a before use" and Eade of the thread 1 thereby becomes trots aligned with the small bore 8a provided in the Wehnelt electrode 8 such previous correction or fine adjustment ¹ the adjusting screw 5a does not work correctly because the thread 1 is heated in the operating state and the metal cylinder 7 is subject to thermal expansion , as a result of which the end of the thread and the small hole 8a can be offset against each other in the direction of alignment »

Since the electron gun as a whole has an expensive and complicated structure, when the thread 1 is used up, a slock having this thread, the electrodes 2 and the insulating plate 3 must be replaced. by removing the Wehnelt · = electrode 8. Characterized each time newly required alignment "of the thread 1 of the yarn end and the small hole 8a in the Wehnelt _o

Object of the invention is eating it "this Geesthacht hurry avoided in an electron gun of the kind su _p ^ ie it is an electron gun for electric ^ = besibrahlungs facilities provided are, the easier voa

309849/0965

Dipping. Heinz Lesssr, foientonwalt D - 8 Munich 81, Cosimastiaße 81 - Telephone: (0811} 95 38 20

■ Design and small size and which allows easy alignment of the thread end and the Wehnelt electrode _o

This object is inventively achieved in _a class, the Wehnelt electrode in the insulating lagekorrigierbar

is defined «, According to the invention, the Wehnelt electrode is:

So no longer fixed on one part to the opposite i

the position of the electrodes holding the thread 1 can be adjusted ^ ■ j but the Wehnelt electrode is the same on the insulating plate

Removable fixed The attachment to the insulating plate!

can be done immediately "but it can also be a support plate!

i be provided _ff against which the WehneIt-Elektrod © uister 2% ji schenk leromen of the insulating plate can be screwed »This not only achieves a significant reduction in the size of the Wehnelt electrode, but also the right-keeping of the alignment of the thread and the Wehnelt electrode even when ironing the thread »■

Due to the described significant reduction @ r size of the Wehnelt d can be produced this _g di © thread · = electrodes and di © supportive insulation with low cost as uniformly trained, exchangeable insert "which is as a whole, fitting, exchangeable when the thread has to be renewed _o The thread can therefore be exchanged easily and simply by the user of the electron gun in that the Wehnelt electrode and the thread can be »aligned« in advance during the manufacture of this replaceable® insert already has the correct alignment between the thread and the Wehnelt electrode under good measuring conditions! the user of the electron gun then only has to insert this spare part in place of the used one _B without further adjustment between Faden and Wehnelt »electrode

For this purpose, the Einsats -as steek unit can be used in this way

• ^ 09849/0985

Dipl.-Ing. Heinz Lesser, patent attorney D - 8 Munich 81, Cosimcstrasse 81 Telephone: (0811) 95 38 20

be designed that the two electrodes on the side of the insulating plate facing away from the thread as a plug are designed to run out. In the insulator of the electron guns; there are two correspondingly arranged sockets for; the supply of the heating voltage into which the plug ends!

the thread electrodes can be easily inserted and removed again

This design of the thread holder and Wehnelt electrode As a plug-in unit, the entire electron gun can be simplified even more in its construction and in its Bigger still more-reduce. This e.g. the production made possible by scanning electron microscopes provided with supports that are easy to carry and set up »

The connection for the Wehnelt electrode can be designed to be pluggable or easily detachable in a similar way as this has been described above in connection with the thread electrodes. In a particularly preferred embodiment, for The voltage supply of the Wehnelt electrode is an elastic one that is under a certain system pressure when in operation elastic contact provided. This elastic contact can be supported in the insulator of the electron gun on a Wehnelt contact provided there and with his Attack the working end of a plate with which the Wehnelt electrode screwed with the interposition of the insulating plate; is.

The invention is explained in more detail with reference to the examples shown in the drawing. Show it

Fig. 1 is a vertical section through an embodiment a well-known electron gun;

2 shows a vertical section through an exemplary embodiment of the electron gun designed according to the invention.

To the embodiment of a known electron gun

3098 4 = 9/0965

Dipl.-lfig. Heinz Lesser, Potentanwalt D -8 Munich 81, Cosimostraße 81 · Telephone: (0811) 95 38 20

according to Fig *! has already been entered at the beginning: “Here let added that the voltage coming from the power source for the Wehnelt electrode 8 via the line 15 and the fixed to the metal connector 12 by the ring 9 Metal cylinder 7 is performed. This also contributes to the complicated design. In contrast, the Wehnelt electrode is of the exemplary embodiment to be described below according to the invention simply connected to a Weh'nelt connection terminal by a spring-loaded contact? which is provided in the insulator of the electron gun · This feature is based on the significant simplification the entire design, together with the characteristic i that a pair of thread electrodes can be inserted into connection sockets connected to a power source as a plug

In the embodiment of the invention shown in FIG. 2, the two ends are a V-shaped thread 21 by spot welding at the lower ends of two Thread electrodes 22-attached by an insulating plate 23 made of steatite or similar material run through and which are sealingly attached to the insulating plate by glass. This insulating plate 23 can be made of mica? and the passed electrodes can be held with nuts-

A Wehnelt electrode 24 having a small bore 24a in its center for the passage of electron beams fixed on the thread-side surface of the insulating plate 23, this between the Wehnelt electrode 24 and a Metal plate 25 is held together'-held together by screws 26 "These screws 26 let you see in threaded holes 25a in the double plate 25 through corresponding holes in a flange of the Wehnelt electrode 24 and accordingly Screw in the provided wide holes 23a- in the insulating plate 23. By tightening the screws 26, the Wehnelt electrode 24 in close contact with the insulating plate 23

309849/0968

Dipl.-Ing. Heinz Lesser, patent attorney D -8 Munich 81, CosimastraGe 81 · Telephone: (0811) 95 38 20

be determined. Due to the width of the holes 23a in the insulating plate 23, the position of the WehneIt electrode 24 opposite the surface of the insulating plate 23 on the thread side to correct the alignment between de: tip 21a des Thread 21 and the small hole 24a of the WehneIt electrode

24 change, in this orientation position by looking at the Set screws 26 «

Each thread electrode 22 runs through the insulating plate 23 and through a wide hole 25b in the double plate 25, without touching them. On the side of the insulating plate 23 facing away from the thread, the thread electrodes 22 run in the above! Ends 22a. These protruding ends 22 a are detachably attached to an electron gun insulator 27 as a connector Power source sockets 28 introduced «

A Wehnelt connection terminal 29, which is fed with a prescribed voltage, is fixed to the electron gun insulator 27, and a spring contact 30 , which is arranged at its lower end, is spring-loaded against the metal double plate 25. As a result, the voltage provided for the Wehnelt electrode is transferred from the Wehnelt connection terminal 29 via the spring contact 30, the double metal plate

25 and the screws 26 are applied to the Wehnelt electrode 24.

It goes without saying that in electron irradiation equipment, during the operation of the interior of an electron gun insulator 27 is held under the atmospheric pressure and the thread side of the apparatus under vacuum as scanning Eiektronenmikroskopen.

To give an example, an energy of 3 volts is applied ^{to the filament electrodes in a small scanning electron microscope 1} *, the filament current is 2 amperes; under these conditions, heat electrons generated on the filament 21 are generated by the Wehnelt electrode 24 with a potential difference of, for example, 500 volts lower than that of the thread

^ 09849/0965

DipJ.-Ing, Heinz Lesser, Potentanv / αΐί D —S Mönchen 81, Cosimasfcraße 81 · Telephone: (0811) 95 38 20

controlled and through the small hole 24a of the WehneIt electrode accelerated in the direction of an anode, not shown, which has a potential difference of 2.B. about 10 kV positive compared to the thread has "

During the maintenance _v inspection or adjustment, the thread side 21 is also exposed to atmospheric pressure, • and the protruding ends 22a of the thread electrodes 22 , which are designed as plugs "are sucked out of the power source sockets 28" In this way, the replaceable insert C " the one from the thread 21 _? the electrodes 22, the insulating plate 23 "of the double plate 25 and the Wehnelt electrode 24 is _t and could also be called cartridge C _v's whole and easily taken out from the apparatus proper al.

Before inserting the insert C into the sockets 28, the thread end 21a and the small hole 24a in the Wehnelt electrode! are already aligned with one another beforehand “ by correcting the position of the Wehnelt electrode 24 relative to the insulating plate 23 - as described above = corrected”. in this way, by changing the thread, the entire insert C can be exchanged «, '

To avoid j. that metallic vapor is reflected by the yarn 21 on the whole surface of the insulating plate 23 during the 'use, which could lead ^ u course circuits between the filament electrodes 22 and the electrodes 22 and the Wehnelt Elektroäe 24, it is expedient to each electrode 22 with to provide a flange 22b separate from the insulating plate and / or to provide a notched groove 24b along the inner path of the Wehnelt electrode 24 which comes into contact with the insulating plate 23 This increases the durability of the insert C enlarged »

30984 9/0965

Claims (5)

7325993 Dipl.-Ing. Heinz Lesser, patent attorney D -8 Mönchen 81, Cosimastiaße 81 - Telephone: (0811) 95 38 20 PATENT CLAIMS 1. ^ electron gun for electron irradiation systems with V_V a pair of electrodes held on an insulating plate for holding and power supply of a thread and with a Wehnelt electrode, characterized in that the Wehnelt electrode (24) can be corrected in position on the Isolation plate (23) is set. 2. electron gun according to claim l _f characterized in that the electrodes (22) on the side facing away from the thread (21) the insulating plate (23) designed as a plug (22a) tapering and in a pair on an insulating body (27) fixed connection sockets (28) are detachably inserted. 3. electron gun according to claim 1 or 2 _f, characterized in that the Wehnelt electrode (24) is connected to the voltage source via an elastic connection contact (3O). 4. electron gun according to claim 3, characterized in that the elastic contact (30) between the insulating body (27) and a metal plate (25) is arranged on the side of the insulating plate (23) facing away from the thread (21) is arranged and adjusting screws (26) reaching through the insulating plate with the Wehnelt electrode (24) communicates. ■ t 5. Electron gun according to one of the preceding claims, marked by _ ',, that 309849/0965 7325993 Dipl.-Ing. Heinz Lesser, patent attorney D - 8 Munich 81, CosimastraGe 81 - Telephone: (0811) 95 33 20 - 9 - ■ the thread (21) is fixed to the thread electrodes (22) by spot welding. 309849/0965 Blank page